Centrifugal compressor



Aug. 25, 1942. WATSON 2,294,143

CENTRIFUGAL commssson Original Filed April 13, 1940 4 sh98tS-Sh9t 1 Hal711 M M51501;

INENTOR ATTORNEY R. M. WATSON 'mRIFueAL COMPRESSOR Original Filed April13. 1940 4 Sheets-Sheet 2 ATTORNEY 8 1 R. M. WATSON CENTRIFUGALCOMPRESSQR Original Filed A ril 13, 1940 4 Sheets-Sheet 5 Ralph .M;Wazifim IN NTOR ATTORNEY 1942. R. M. WATSON CENTRIFUGAL COMPRESSOROrigin'al Filed April is, 1940 ATTORNEY 4Sheets-Sheet 4 Patented Aug.25, 1942 CENTRIFUGAL COMPRESSOR Ralph M. Watson, Bloomfield, N.'J.,assignor to Worthington Pump. and Machinery Corporation, Harrison, N.J., a corporation of Dela- Ware Original application April 13, 1940,Serial No. 329,498. Divided and this application April 2, 1942, SerialNo. 437,405

7 Claims.

This invention relates to centrifugal gas or vapor compressors, and moreparticularly to a centrifugal compressor for use in refrigeratingsystems for handling a volatile liquid of low vapor pressure and highdensity, such for example as trichlorofluoromethane, methylene chlorideor the like.

, An object of the present invention is to provide in a centrifugalcompressor means for delivering lubricating oil to the bearings of thecompressor at a pressure slightly in excess of the-pressure in thecompressor at either end of the bearings at the shaft openings toprevent leakage of vapor or gas through the shaft bearings and toprovide a lubricating system embodying a plurality of chambers undervarious degrees of pressure in the return line of the lubricant from thebearings to the circulating oil pump so as to separate the entrainedrefrigerant from the oil.

The present application is a division of my ap- With these and otherobjects in view, as may appear from the accompanying specification, theinvention consists of various features of. construction and combinationof parts, which will be first described in connection with theaccompanying drawings, showing a centrifugal compressor of the preferredform embodying the invention, and the features forming the inventionwill be specifically pointed out in the claims.

In the drawings:

Figure 1 is a side elevation of the improved centrifugal compressor.

Figure 2 is a top plan view of the compressor.

Figure 3 is an end view of the compressor looking toward the suction orinlet end.

Figure 4 is a longitudinal sectionthrough the compressor taken'on theline 4-4 of Figure 2.

The centrifugal compressor of the present invention utilizes theprinciple of impeller and discharge volute in lieu of the generalpractice of employing difiusion vanes in the discharge passage of thecompressor with the result that the eillciency of the compressor ismaterially increased and frictional losses diminished. The,

compressor, comprises a horizontally split casing I0, through the axisof which extends the driving shaft II. The driving end of the shaft Ilmay be connected by any approved type of coupling I! with any approvedtype of prime mover.

The shaft It carries the various impellers of the centrifugalcompressor, the number of which and consequently the number of stages ofthe compressor depends entirely upon the conditions of plication SerialNo. 329,498, filed April 13, 1940.

the installation in which the compressor is to be incorporated and thework to be performed by the compressor.

Referring specifically to the drawings, the easing I0 has a suction-orinlet connection I4 at one end thereof, through which the vapors to becompressed enter the compressor. The inlet passage It has a butterflyvalve or damper i5 therein, by means of which the active, vapor'passingcross-sectional area of the passage Hi may be regulated. This butterflyvalve l5 may be operated by any suitable mechanism. A hand wheeloperated gear and pinion structure is shown in Figures 1 and 3 of thedrawings, in which the gear I5 is rotated by the pinion l6. The pinionI6 is in turn rotated by a hand wheel ii. The gear I5 is mounted upon orsuitably connected to the carrying shaft I8 of the valve IS. The inletpassage l4 curves upwardly and laterally into the suction or inlet eye20 of the first or suction stage discharges into a double or twin volute30 formed of the two volute passages 3i and 32, clearly shown in Figure4 of the drawings. The defining v walls 33 of the double volute passagescurve circumferentially and laterally into the suction passage 34, whichopens into the inlet-or suction compressor was designed. This provisionof the twin or double volute, together with the staggered arrangement ofthe volutes of the remaining stages of the compressor, willapproximately take careof or balance any radial thrust which .may occurin the entire compressor during off standard operating conditions. I

The second stage impeller 36 discharges into a single volute 31, whichis connected by a suitable passage to the suction-eye 38 of the thirdstage impeller 39. The passage which connects the discharge volute 31 ofthe second stage impeller 36 to the thirdstage impeller 39 is shown inthe drawings as comprising the nozzles 40 and 4|,

which areformed on the casing IQ of the com pressor and are connected bya U-coupling 42. 1

is shown arranged to permit the introduction of vapor into the thirdstage of the compressor, it is to be understood that such a connectionmay be connected at any suitable point to the casing of the compressorto permit the introduction of vapor into any one of the stages of thecompressor following the first stage. The third stage impeller 39, whichin the construction shown in the drawings is the final stage, dischargesthrough its volute 45 into a. discharge nozzle 46.

In the drawings, wherein a three stage compressor is shown, it will benoted that the first two stages, that is the impellers 2i and 36, aredisposed in a parallel pair, with the back of the first stage impeller2| facing the suction of the second stage impeller 36. Thus the combinedendthrust of these two stages will be toward the right (Fig. 4), whilethe impeller 39 of the third stage of the compressor is disposed in adirection opposite to that of the impellers 2i and 38, with its backfacing the back of the second stage impeller 36. Consequently the endthrust of the third stage impeller 39 will be toward the left (Fig. 4)and in an opposite direction to the end thrust of the impellers 2i and35. Since impeller 39 is the highest pressure impeller and the endthrust produced by this impeller will be substantially equal to the endthrust produced by impellers 2i and 36, counterbalancing end thrusts areset up in opposite directions in the compressor which will approximatelybalance each other and permit the use of a simple, inexpensive thrustbalancing bearing as shown at 57 in Figure 4 of the drawings.

Centrifugal compressors of the type above described and illustrated inthe drawings, when used or employed in refrigeration or air conditioningsystems generally receive the vapor or refrigerant gases into the firststage suction at a pressure of approximately seven pounds (7 lbs.)

' below atmosphere. The third or final stage of the compressor receivesthe vapor into its suction at a pressure slightly'above or'belowatmosphere, for instance atmosphere plus or minus three pounds (3 lbs.).Thus it will be seen that the opposite ends of the interior of thecasing ID will be subjected to subatmospheric pressure at the initialinlet end of the casing and to approximately atmospheric pressure at theother pressor through a combination of close fittingbearings for theshaft and the lubricating system for such bearings, while a specialmechanism is provided for sealing the casing when the compressor isidle.

Due to the arrangement of the impellers in the compressor as abovespecifically described. not only is end thrust in the compressorapproximately counterbalanced, but the arrangement also provides thatthe shaft opening at the initial suction end of the compressor issubjected to the pressure of the vapor at the initial inlet, while theshaft opening 5| at the opposite end of the casing is subjected to thesuction pressure of the vaporatthe third stage suction.

Therefore neither of these openings will be subjected to the highestpressure developed in the compressor, which fact materially simplifiesand reduces the cost of'the mechanism for sealing such'openings in that,for one thing, it reduces the pressure of the lubricating'oil.

An oil reservoir 52 is provided in which an oil pump 53, of any approvedconstruction, is mounted. The oil pump 53 is driven from the shaft I!through a coupling structure 54, shaft 55 and suitable transmission 56,which in the present instance is shown as beveled gears.

At the initial suction end of the compressor a bearing structure 5'! isprovided which is carried by the casing in and which has suitable oilducts 58 extending radially therethrough to lubricate the bearing. Oilis supplied to the ducts 58 from an oil inlet line 59 which receives theoil from the discharge end of an oil cooler 56. The oil is pumped by thepump 53 through a suitable piping system 6! into and through the cooler60. Pressure regulating valves 62 of any approved type or constructionmay be connected in the pipe line 6| for the purpose of regulating thepressure of the oil if it is desired. The oil passes through the bearing51 in both directions and that which passes through the bearing inwardlytoward the compressor passes into a chamber 63 and returns through adrain opening or drain openings 64 through the hearing into the chamber65. 1 The oil which passes through the bearing outwardly or away fromthe casing l0 passes into the chamber 65 and from this chamber drainsinto the reservoir 52. .The chamber 65 is under a subatmosphericpressure. That is, it is under the pressure of the vapor as it entersthe initial inlet of the compressor. A stationary bushing 66 is mountedabout the shaft ll between the bearing 51 and the impeller 2i.

This bushing has its inner surface provided with a, plurality oflongitudinally spaced circumferential grooves, as shown at 61, and itprevents creeping of oil along the shaft into the compressor. Thebushing 66 has an oil collection chamber 68 formed therein with which adrain opening 69 communicates. The drain opening leads back to thechamber 83 so that any oil which would pass through the bushing 66 intothe chamber 68 would be drained back eventually into the reservoir 52.

At the opposite end of the casing 10 from the bearing 51 a secondbearing 10 for the shaft ll is provided. While the particularconstruction of the bearing and its companion parts which form the sealfor the casing ID are the subject matter of Patent No. 2,254,862, issuedSeptember 2, 1941, the structure will be specifically described hereinto establish its action and cooperation in the general combination ofthe compressor.

The bearing 10 is a tight-fitting bearing and quently gets slightly outof alignment due to various causes such as whip in the shaft whenrotating at high speeds, means are provided to maintain propertight-fitting engagement between shaft and hearing at all times so as toprovide an effective seal for the shaft opening in the casing. Thebearing I0 is connected to the casing I 0 by a flexible disc H. Thisdisc H is made of strong, flexible metal so that it will flex duringoperation of the compressor to permit movement of the bearing II! withmovement of the shaft H other than rotary movement so as to maintain atall times the tight flt between the bearing 'of annular grooves 84 -asuitable drain 85 into the chamber 12.

and shaft to preserve the seal and to preventexcess wear. on thehearing. The shaft opening opens into a chamber 12, into which the innerend of the bearing also extends, while the outer end of the bearingextends into a chamber 13. The chamber 12 is subjected to a pressure ofapproximately atmosphere, that is, a pressure slightly above or belowatmosphere, namely the suction pressure of the vapor at the inlet of theimpeller 39, while the chamber 13 is subjected to atmospheric pressure.Oil is delivered to the interior of the bearing III intermediate itsends from the oil inlet line 14 through a suitable connection 15. Theinlet line 14 receives oil from the outlet end of the oil cooler 60. Theoil passes longitudinally through the bearing in both directions, partof it passing intothe chamber 12 from which it drains through suitabledrain outlets l1 and pipe connections 18 to a collection chamber 19.From that. chamber 19 the oil returns to the reservoir 52 through thepiping system 80. The oil which flows outwardly through the bearing intothe chamber 13 passes through suitable drain openings 8| into thecollection chamber 82, from which it passes through the collectionpiping system 80 back to the reservoir 52.

The interior of the oil chamber 52 is under the same pressure as theshaft opening 50, viz., the pressure of the vapor at the initial inletto the compressor. By having it under such relatively low pressurerefrigerant which is carried thereto by the oil and is consequentlydelivered to the chamber at a pressure in excess of the pressure thereinis released.

A bushing 83 is positionedbetween the chamber 12 and the impeller 39,similarin its construction to the bushing 66, having a pluralityalong-its bore, and is provided with an oil collection chamber 85 fromwhich oil drains through The bushing 83 forms a dam to hinderleakage ofoil into the suction of the impeller 39.

The construction of the bearing 10 and the lubrication of the bearing inthe manner above spaced longitudinally.

, prevent oil from described will effectively seal the opening 5| fromboth leakage of vapor out of the casing and leakage of air into thecasing, during the operation of the compressorf But when the compressoris shut down the delivery of lubricating oil to the hearing will bestopped and consequentlyit is necessary to provide means to preventeither internal-leakage of-air or external leakage of vapor out of thecasing'through the opening 5l at such times.

The structure provided for this purpose includes a packing collar 90,which is of any suitable type of soft, resilient material notsusceptible to objectionabl corrosion or deterioration under action ofthe refrigerant vapor compressed.

pivotally suported at 95 and is connected to the sleeve 93 and to apressure actuated piston 96,

' which is shown as connected to a bellows 91.

The piston 96 is urged inwardly, compressing the bellows Si, by a spring98. Duringthe operation of the compressor the tension of the spring' 98is overcome by the pressure of oil from the lubricating system of thecompressor, which is delivered to the interior of the bellows-91 throughthe connection 99, thus expanding the bellows,

and forcing the piston 96 outwardly, which moves the sleeve 93outwardly, relieving the soft, resilient packing collar 90 of pressurefrom the sleeve 93. When the compressor is stopped and consequently thepressure of oil in the bellows 91 shaft to form a tight seal about theshaft. For

the purpose of insuring the movement of the packing collar 90 into apressure relieved position during the operation of the compressor, afollower lfll is mounted about the shaft I I and engages the inner sideof the collar 90 inwardly of the shoulder 9|. A spring 12 engages thefollower llll for urging itoutwardly thus moving the collar 90 out of.tight sealing engagement with the shaft when the collar is relieved ofpressure of the sleeve. 93.

A dish-shaped slinger I03 is mounted on the shaft II for rotationtherewith, between the collar 90 and the bearing HI, and in the chamber13. This dish-shaped slinger I03 is provided for throwing oil awayfrom'the shaft ll so as to leaking along the shaft to the collar 90. 4

It will be understood that the invention is not to be limited to thespecific construction or arrangement of parts shown, but that they maybe widely modified within the invention defined by the claims. v 1 i AWhat is claimed is: 1

1. In a centrifugal compressor, a casing, a driv ing shaft, a pluralityof stage impellers on said shaft, said casing provided with openings'atits ends through which said shaft extends,'said impellers located andarranged whereby the-casing adjacent one of said openings will have'amaximum pressure therein less than the final discharge pressure of thecompressor and the casing adjacent to the other opening will haveinitial suction pressure of the compressor therein, bearings for saidshaft outwardly of said openings, a chamber about the bearing at thesuction end i of the compressor and subject to initialsuction pressureof the compressor, a chamber'about a part of the bearing adjacent to thehigher pressure end of the casing and subject to the pressure in thecasing the maximum pressure of which is less than the discharge pressureof the compressor, a third chamber about the remaining part of saidsecond-namedbearing and subjectto'fapproximately atmospheric pressure,an oil "reservoir for supplying oil to said bearings under pressureslightly in excess of the pressures at both ends of the bearings, andbushings carried by said casing between said bearings and adjacentimpellers, said bushings. having oil collection chambers and passagestherein for collecting and draining oil back to the bearingenclosingchani-- her adjacent thereto.

2. In a centrifugal compressor, a casing, adriving shaft, a plurality ofstage impellers on said shaft, said casing provided with openings at itsends through which said shaft extends, said impellers located andarranged whereby thecaslng adjacent one of said openings will have amaximum pressure therein less than the finaldis charge pressure of thecompressor and the casing adjacent to the other opening will haveinitial suction pressure of the compressor therein, bearin the casingthe maximum pressure of which is less than the discharge pressure of thecompressor, a third chamber about the remaining part of said secondnamed bearing and subject to approximately atmospheric pressure, an oilreservoir, said chambers all draining back to said reservoir, and meansin said reservoir for supplying oil to said bearings under pressureslightly in excess of the pressures at both ends of the bearings, saidoil reservoir being subject to the and to release entrained refrigerantcarried to the reservoir by the returning oil.

5. In a centrifugal compressor, a casing, a driving shaft, a pluralityof stage impellers on said shaft, said casing provided with openings atits ends through which said shaft extends, said impellers located andarranged. whereby the casing adjacent one of said openings will have amaximum pressure therein less than the final discharge pressure of thecompressor and the cusing adjacent to the other opening will haveinitial suction pressure of the compressor therein, bearings for saidshaft located exteriorly of said shaft openings in the casing, a chamberabout a part of the bearing adjacent to the higher pressure end of thecasing and subject to the pressure in the casing the maximum pressure ofwhich is less than the discharge pressure of the compressor, a supportfor said bearing at the initial suction pressure of the compressor so asso high pressure end of the casing, said support to permit the oil todrain freely thereto and to release entrained refrigerant carried .tothe reservoir by the returning oil.

- 3. In a centrifugal compressor, a casing, a driving shaft, a pluralityof stage impellers on said :5

shaft, saidmasing provided with openings at its ends through which saidshaft extends, said impellers located and arranged whereby the casingadjacent one of said openings will have a maximum pressuretherein lessthan the final dls- 80 charge pressure of the compressor and the casingadjacent to the other opening will have initial suction pressure of thecompressor therein, bearings for said shaft located exteriorly of saidshaft openings in the casing, a chamber about apart 38 or the hearingadjacent to-the' higher pressure end of thecasingand subject to'thepressurein thecasing themaximumpressureofwhichisless than the dischargepressure of the compressor, a

of said chamber, an oil reservoir, and means in said reservoir forsupplying. oil' to the hearing at the high pressur end oflthe casingunder presforming the outer wall of said chamber, an oil reservoir,means in said reservoirfor supplyin oiltothebearingatthehighpressuree'ndofthe casing under pressure slightly in excess of thepressurcinthechambertoformasealin-tbe bearingto prevent leakage ofrefrigerant through the hearing, means cooperating with said bearingsupport to form an outer chamber outwardly of said first named chamber,said outer chamber enclosing the portion of said hearing which is notenclosed in said first named chamber and being subject to approximatelyatmospheric pressure, and means for draining oil from said chambers tosaid oil reservoir, said oil reservoir being subject to pressure lowerthan the pressure in thechamberssoastopermittheoiltodrain freely theretoand to release entrained refrigerant carried to thereservoir by thereturning oil.

- 6. In a centrifugal compressor, a casing, a

' support for said hearing at the ,high pressure end 40 driving shaft, aplurality ofstage impellers on of the casing, said support forming theouter wall saidshaftsaidcasingpro withopeningsat its ends through whichsaid shaft extends, said impellers located and arranged whereby theeasing adjacent one of said openings will have a sure slightly in excessof the pr'essure'in thegmaximum pressure thereinlessthanthe finalchamber to form a seal in the bearing to' prevent leakage of refrigerantthrough the bearing.

' 4. In a centrifugal compressor, a casing, a driving shaft, a pluralityof stage impellers on said shaft, said casing provided with openings atits so ends through which said shaft extends, said impellers located andarranged whereby the casing adjacent one of said openings will have amaximumpressurethereinlessthantheiinaldischarge pressure of thecompressor and the casing gs adjacent to the other opening will' haveinitial suction pressure of the compressor therein, bearings for saidshaft located exteriorly of saidshaft openings in the casing, a chamberabout a part of the bearing adjacent to the higher pressure end ,6

ofthec'asingandsubjecttothepressureinthe casing the maximum pressure ofwhich is less than the discharge pressure of the compressor, a supportfor said bearing at the high pressure end of the casing, said supportforming the outer wall of said chamber, an oil reservoir, means in said,reservoir for supplying oil to the hearing at the high pressure and ofthe casing under pressure slightly in excess of the pressure in thechamber to form a seal through the bearing to prevent 0 leakage ofrefrigerant through the bearing, means for draining oil from saidchamber to said 011- reservoir, and said oil reservoir being subject topressure lower than the pressure in thechamdischargepressureofthecompressorandthc casing adjacent to the otheropening will have initial suction pressure of the compressor therein,bearings for said shaft located exteriorly of said shaft openings in thecasing, a

aboutapartofthcbearingadjaoenttothehigherpressurcendofthecasingandsubjecttothcpressurcintheccsingthemaximumpressureofwhichislessthanthedischargepressureofthe compressor, a support forhearing at the highpremureendotthecasinmsaidsupportformingtheouterwallofsaidchambenanoilreservoir,andmeansinsaidreservoirforsupplyingoiltothebearingatthchighpressurcendamaximumpressurethereinless'thanthennal bersoastopermittheoil todrainfreely thereto discharge pressure of the compressor and the casingadjacent to the other opening will have initial suction pressure of thecompressor therein, bearings for said shaitlocated exteriorly of saidshaft openings in the casing, a chamber about a part of the bearingadjacent to the higher pressure end of the casing and subject to thepressure in the casing the maximum pressure 01' which is less than thedischarge pressure 01' the compressor, a support for said bearing at thehigh pressure end of the casing, said support forming the outer wall ofsaid chamber, an oil reservoir, means in said reservoir for supplyingoil to the bearing at the high pressure end oi the casing under pressureslightly in excess of the pressure in the chamber to form a seal in thebearing to prevent leakage of refrigerant through the bearing, meanscooperating with said bearing 'sup-.

port to form an outer chamber outwardly of said first named chamber,said outer chamber enclosing the portion of said hearing which is notenclosed in said first named chamber and being subject to approximatelyatmospheric pressure, means for draining oil from said chambers to saidoil reservoir, said oil reservoir being subject to pressure lower thanthe pressure inthe chambers was to permit the oil to drain freelythereto and to release entrained refrigerant carried to the reservoir bythe returning'oil, and a bush.

'ing carried by said casing between said chamber and the adjacentimpeller, said bushing having an oil collection chamber and passagestherein for-collecting and draining 011- back to the chamher. 4 I aRALPH M. wA'rsou,

